Any of them as long as they have networking support of some sort (You don't want to be doing something without at least a wrapper for networking, shit like HTTP requests and all.)
But yeah, the language really doesn't matter. Whatever you're comfortable with, it all comes down to preference. People like Java because it's good at working with lots of data like combolists. Lots of people like C# after the xNet libs were released for easy proxy support. Me? I like Go because it's like C but not low-level enough to be incomprehensible (and needing 40 lines of code to initialize a simple HTTP client, or whatever.)
It really just boils down to whatever works for you. Pick a language, start learning it, once you feel comfortable with syntax, look into the networking side of things.
Help me out 
